Simoes, Brian wrote:
> 
> Volks,
> 
> My wife and I are in the process of purchasing an '85 Westy GL and I was hoping
> to gain some basic knowledge on the theory/operation of combustion
> motors...especially as it relates to the motor in my Westy.
> 
(snip)

Brian,

Please don't think I am trying to insult your intelligence by telling 
you this but I used to teach aircraft systems, including normal and 
emergency operational procedures, to fighter pilots. I taught them what 
I am going to tell you. When the old fire goes out and your engine stops 
turnin' and burnin', you can't just pull your Phantom over to the side 
of the cloud, park and pull out the manual. You have to do your 
troubleshooting quickly and accurately or you have to jettison the 
airplane and spend the next six months filling out paperwork equivalent 
to the gross weight of the aircraft.

All internal combustion four cycle engines(gasoline or diesel piston or 
turbine) work basically the same way. The four cycles are INTAKE, 
COMPRESSION, COMBUSTION and EXHAUST. In layman's terms, all engines 
SUCK, SQUEEZE, BANG and BLOW. They intake(suck) air, compress(squeeze) 
air, combust(bang) about 15 parts air to 1 part fuel and exhaust(blow) 
the hot expanding gases out of the engine. In automotive engines, the 
energy is used to drive a set of pistons down and the piston rods and 
eccentric crankshaft convert the linear motion into rotary motion. The 
heavy flywheel takes care of getting the pistons back up again.

Two things need to be added to the 4 cycles mentioned above to complete 
the understanding of how an engine works. A measured amount of fossil 
fuel has to be introduced(carbureted or injected) into the compressed 
air at the proper time(valve timing or diesel pump timing) and a source 
of ignition has to be applied at the right time(ignition timing) to 
initiate(diesels and turbines) and often to sustain(pistons) the 
combustion of fuel and air.

So, if you understand the following, you will understand the operation 
of your vehicle's engine. I fall back on this for troubleshooting 
whenever I'm faced with a puzzling engine problem that defies easy 
solution.

All 4 cycle engines SUCK��SQUEEZE��BANG��BLOW.

Oops, forgot something.

All 4 cycle engines SUCK��SQUEEZE���FUEL��FIRE���BANG��BLOW

All together now���SUCK��SQUEEZE���FUEL��FIRE���BANG��BLOW

And, that's all you need to know.

Oh yes. In aircraft anyway, in the absence of visible(oil leak, fire, 
etc.) or audible(grinding, banging noises) symptoms, most engine 
failures by far are caused by an interruption of fuel flow, followed by 
an interruption of air flow. The least likely cause is an interruption 
in electrical ignition but I suspect this may not hold true for 
automotive piston engines. Things are also complicated somewhat by the 
need to maintain engine temperatures within a narrow range(air or liquid 
cooling) combined with the cooling properties of engine oil. But, that's 
a subject for someone else on another day.

I hope this helps. I have been told I have a tendency to tell someone 
who asks for the time how to build a watch. I hope I didn't this time.

Jerry Hart
'84 Wolfie